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Proceedings Paper

Effect of scatter radiation on image noise in cone-beam CT
Author(s): Masahiro Endo; Takanori Tsunoo; Nobuyuki Nakamori
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Paper Abstract

Cone beam CT has a capability of 3-dimensional imaging of large volumes with isotropic resolutions, and has a potentiality of 4-dimensional imaging (dynamic volume imaging) because cone beam CT acquires a large volume data with one rotation of X-ray tube-detector pair. However, one of the potential drawbacks with cone beam CT is larger amount of scattered X-rays. These X-rays may enhance the noise in reconstructed images, and thus affect low contrast detectability. The aim of this work was to estimate scatter fractions and effects of scatter on image noise, and was to seek methods of improving image quality in cone beam CT. First we derived a relationship between the noises in reconstructed image and in X-ray intensity measurement. Then we estimated scatter to primary ratios in X-ray measurements, using a Monte Carlo simulation. From these we estimated image noise in clinical relevant conditions. The results showed that scatter radiation made a substantial contribution to the image noise. However focused collimators improved it, because they decreased scatter radiation drastically while keeping the primary radiation nearly the same level. A conventional grid also improved image noise though the improvement was less than that of focused collimators.

Paper Details

Date Published: 25 April 2000
PDF: 8 pages
Proc. SPIE 3977, Medical Imaging 2000: Physics of Medical Imaging, (25 April 2000); doi: 10.1117/12.384527
Show Author Affiliations
Masahiro Endo, National Institute of Radiological Sciences (Japan)
Takanori Tsunoo, National Institute of Radiological Sciences (Japan)
Nobuyuki Nakamori, Kyoto Institute of Technology (Japan)

Published in SPIE Proceedings Vol. 3977:
Medical Imaging 2000: Physics of Medical Imaging
James T. Dobbins; John M. Boone, Editor(s)

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